2014 Italian GP Practice Three: Nico Rosberg hits gearbox trouble as Hamilton flies

The reliability pendulum swung between the title-duelling Mercedes drivers on Saturday morning at Monza as Nico Rosberg ran into gearbox trouble as Lewis Hamilton flew to a dominant fastest time.

In a near-role reversal of the championship rivals' fortunes from Friday afternoon, when Hamilton lost much of the session through a misfire, points leader Rosberg was forced to abandon his Practice Three after just three laps on Saturday morning when a gearbox problem struck his W05.

It meant the 29-point championship leader missed all of the session’s low-fuel qualifying simulations – which Hamilton, predictably, went on to dominate – and appeared to raise the potentially dramatic spectre of a five-place gearbox change penalty for Rosberg should Mercedes’ engineers not be able to resolve the glitch before qualifying.

"@nico_rosberg forced to sit out most of that session with a gearbox issue that the team are working very hard to fix before quali!" Mercedes tweeted after P3.

However, Sky Sports F1's Ted Kravitz later tweeted: "No gearbox change or grid penalty for Rosberg, Merc can change internals as rules permit."

With a second fastest time of the weekend all-but assured for Hamilton as a result of his team-mate's woes, the Briton displayed the searing pace he had already showed a day earlier P1 with a stunning lap of 1:25.519 on the medium tyres to outpace Ferrari’s Fernando Alonso by four tenths of a second.

Hamilton, who has suffered most of Mercedes' unreliability in qualifying and races this season, last claimed a pole and outqualified Rosberg at May's Spanish GP, but now appears to hold the advantage at Monza.

In any case, Mercedes again look comfortably the fastest for a single lap around the high-speed circuit, although the battle for third place downwards looks set to be closely-contested between Williams and home-favourites Ferrari in particular.

Alonso's second place ahead of the Williams pair Valtteri Bottas and Felipe Massa in the super-fast FW36s was particularly well timed given Ferrari President Luca di Montezemolo made his traditional Monza entrance on Saturday morning, the Italian arriving at the circuit this year at the centre of frenzied speculation that he is about to stand down from his long-held role.

Having topped the early stages of the session, Jenson Button claimed a very solid fifth for McLaren ahead of Sebastian Vettel who again proved Red Bull's lead runner this weekend. Kimi Raikkonen was seventh in the second Ferrari, four tenths back on Alonso.

Daniil Kvyat was the second-fastest Renault-powered runner in eighth but the Toro Rosso rookie is likely to start Sunday's race in the lower reaches of the order after he became the first driver this season to have a sixth engine installed in his car, triggering a ten-place grid penalty.

Daniel Ricciardo and Nico Hulkenberg completed the top ten but the second Force India of Sergio Perez completed only ten laps after he stopped on track when his VJM07 lost drive.